pressure sensitivity
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Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 19
Author(s):  
Pengfei Zhang ◽  
Chao Wang ◽  
Liuwei Wan ◽  
Qianqian Zhang ◽  
Zidan Gong ◽  
...  

An opto-microfluidic static pressure sensor based on a fiber Fabry-Perot Interferometer (FPI) with extended air cavity for enhancing the measuring sensitivity is proposed. The FPI is constructed in a microfluidic channel by the combination of the fixed fiber-end reflection and floating liquid surface reflection faces. A change of the aquatic pressure will cause a drift of the liquid surface and the pressure can be measured by detecting the shift of the FPI spectrum. Sensitivity of the sensor structure can be enhanced significantly by extending the air region of the FPI. The structure is manufactured by using a common single-mode optical fiber, and a silica capillary with the inner wall coated with a hydrophobic film. A sample with 3500 μm air cavity length has demonstrated the pressure sensitivity of about 32.4 μm/kPa, and the temperature cross-sensitivity of about 0.33 kPa/K.


2021 ◽  
Author(s):  
Ernest Henry Rutter ◽  
Julian Mecklenburgh ◽  
Yusuf Bashir

Abstract. The effective pressure sensitivity of gas flow through two shales (Bowland and Haynesville shales) and a tight gas sandstone (Pennant sandstone) was measured over the typical range of reservoir pressure conditions. These are low permeability rocks such as can be exploited as caprocks above reservoirs that might be developed to store compressed air, methane, hydrogen or to bury waste carbon dioxide, all of which may become important components of the forthcoming major changes in methods of energy generation and storage. Knowledge of the petrophysical properties of such tight rocks will be of great importance in such developments. All three rocks display only a small range in log10 permeability at low pressures, but these decrease at dramatically different rates with increasing effective pressure, and the rate of decrease itself decreases with pressure, as the rocks stiffen. The pressure sensitivity of the bulk moduli of each of these rocks was also measured, and used to formulate a description of the permeability decrease in terms of the progressive closure of narrow, crack-like pores with increasing pressure. In the case of the shales in particular, only a very small proportion of the total porosity takes part in the flow of gases, particularly along the bedding layering.


Author(s):  
Lei Shi ◽  
Licheng Jia ◽  
Chongbin Liu ◽  
Hongbin Yu ◽  
Chengliang Sun ◽  
...  

Abstract In this paper, a low noise amplification circuit is designed for aluminum nitride (AlN)-based piezoelectric micromachined ultrasonic transducers (PMUTs) with three diffenent sensing configurations. The acoustic pressure sensitivity and noise resolution of PMUTs corresponding to different readout configurations are analyzed and characterized. With the differential readout configuration, the acoustic pressure sensitivity of the PMUTs is improved by 5.76 dB (re: 1 V/μPa) on average, and the noise resolution is reduced by about 8 dB at 500 Hz (re: 1 μPa/√Hz). Compared to the conventional readout configuration, both theoretical analysis and measurement results show that the output voltage of PMUTs is doubled with the differential readout configuration and thus the acoustic pressure sensitivity is improved. Moreover, the noise resolution of PMUTs is reduced and thus the signal-to-noise (SNR) is improved. This work offers new insight on improving the receiving performance of PMUTs.


Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1340
Author(s):  
Qi Ding ◽  
Hongliang Wang ◽  
Hanqiang Zhang ◽  
Xiao Huang ◽  
Xiaolei Sun ◽  
...  

Capacitive micromachined ultrasonic transducers (CMUTs) have been indispensable owing to their resonance characteristics in the MHz frequency range. However, the inferior pressure sensitivity and linearity of traditional CMUTs themselves cannot meet the actual demands of micro-pressure measurements. In this paper, two novel CMUTs are proposed for the first time to improve the measuring performance of micro-pressure in the range of 0–10 kPa. The core concept of the enhancement is strengthening membrane deformability by partly adjusting the CMUT framework under the combined action of electrostatic force and uniform pressure. Two modified structures of an inverted frustum cone-like cavity and slotted membrane are presented, respectively, and a finite element model (FEM) of CMUT was constructed and analyzed using COMSOL Multiphysics 5.5. The results demonstrate that the maximum displacement and pressure sensitivity are improved by 16.01% and 30.79% for the frustum cone-like cavity and 104.22% and 1861.31% for the slotted membrane, respectively. Furthermore, the results show that the width uniformity of the grooves does not influence the characteristics of the membrane, which mainly depend on the total width of the grooves, greatly enriching design flexibility. In brief, the proposed structural designs can significantly improve the micro-pressure measurement performance of the CMUT, which will accelerate the rapid breakthrough of technical barriers in the fields of aerospace, industry control, and other sensing domains.


2021 ◽  
Author(s):  
Andrew C.H. Au ◽  
◽  
Brenda H.S. Lam ◽  
Y.C. Kwan ◽  
Angus K.K. Tung

The Standards and Calibration Laboratory (SCL) in Hong Kong has developed a system for calibration of quarter-inch working standard (WS3) microphones which automates the measurement process and generates digital calibration certificates (DCC) to meet the growing demand for microphone calibration services in Hong Kong. This paper describes (i) the method of determining the pressure sensitivity of a microphone combination unit from 20 Hz to 20 kHz by the comparison technique in accordance with the International Standard IEC 61094-5, (ii) the measurement model and uncertainty evaluation, and (iii) the automatic system which facilitates the calibration process and generation of a digital calibration certificate.


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